Culture of mycobacteria from the blood has not been used routinely as a method for diagnosing mycobacterial infections. It has been found, particularly with AIDS patients, that mycobacteremia can be detected using a new lysis-centrifugation blood culture system (ISO) as well as with a radiometric blood culture system (Bactec). It was thought that a combination of both methods would yield a more rapid and sensitive blood culture method, than the ISO alone so a trial evaluation is now in progress. Blood from AIDS patients known to be infected with mycobacteria from any site is collected in Isolator blood culture tubes. After lysis and centrifugation, the remaining pellet is cultured onto routine mycobacterial culture media as well as into a Bactec blood culture vial. Results of this study will indicate how useful an adjunct the Bactec System would be in either faster detection or greater sensitivity than use of the Isolator onto routine media alone. This comparative study is being done in conjunction with a clinical study to evaluate the efficacy of therapy in eradicating mycobacterial infection. Serial blood cultures on infected patients are being used to monitor therapeutic response and also to help tailor specific antibiotic coverage for individual patients.